This invention relates generally to solid-state electronic timepieces having an electro-optic display capable of selectively presenting several aspects of time information, each of which is settable, and more particularly to an electronic logic system for a solid-state timepiece which is controlled by a manually-operated coding key and is adapted to effect a selection of a desired display aspect of the setting mode therefor.
The term solid-state electronic timepiece, as used herein, is limited to timepieces provided with an electro-optic time display and having no moving parts. The traditional, spring-powered mechanical watch produces rotary motion for driving gear works that operate the moving hands or time indicators. In those electronic watches which also have a moving hand read-out, the oscillations of a balance wheel or the vibrations of a tuning fork are electronically-sustained, those oscillations or vibrations being converted into rotary motion for driving the gear train. Hence moving parts are included in electronic timepieces of this type.
However, in recently-introduced types of solid-state electronic watches, electrical pulses derived from a crystal-controlled time base serve to actuate a multi-digit electro-optic display formed either by light-emitting diodes (LED) or by liquid-crystal display elements (LCD). Hence in such solid-state electronic timepieces, no moving parts are entailed. In such solid state watches, the high-frequency output of the time base is fed to a frequency converter constituted by a chain of integrated circuit divider stages. The output of the converter consisting of low-frequency timing pulses (i.e. 1 Hz), is applied to a display actuator in the form of a miniature time-computer module that counts the input pulse train, encodes it in binary form and then decodes and processes the results so as to provide the appropriate signals at the display stations.
In a battery-operated electronic watch having moving parts, such as that disclosed in U.S. Pat. No. 2,971,323, the time display is continuous, yet the efficiency of the movement is such that the operating life of the small power cell is well over a year. But in a solid-state watch, the power requirements of the electro-optic display in the case of an LED type of display, are relatively high; hence should the display be continuous, the life of the battery would be quite brief.
It is for this reason that commercially-available types of solid-state watches having an LED display are provided with a normally-quiescent display that is turned on only when the user depresses a push-button demand switch, thereby conserving power and prolonging the life of the battery. In one such watch, as disclosed in U.S. Pat. Nos. 3,756,013 and 3,759,031, the LED display is programmed so that upon merely touching the push-button switch, the minutes and hours are indicated for an interval of one and one-quarter seconds, whereas continued depression of the switch causes the minutes and hour data to fade and the seconds to appear and to continue to count as long as the button is held in.
In this solid-state timepiece, precise computation of time is continuous and independent of whether or not it is displayed, so that the moment the switch is depressed, timing signals are applied to the display. In solid-state watches of the type disclosed in U.S. Pat. Nos. 3,756,013 and 3,759,031, setting of the readings is accomplished by separate switches, one for "hours" and the other for "minutes". These setting switches are actuated by inserting a probe in a recess giving access thereto. When the "hours" set switch is operated, the "hours" read-out advances rapidly without disturbing the setting of the minutes and seconds. When the "minutes" setting switch is actuated, the "seconds" are automatically zeroed, while the minutes are advanced to the desired setting. In a similar electronic watch of this type as disclosed in U.S. Pat. No. 3,817,021, the setting switches are operated by means of external magnets to avoid sealing problems.
Hence, in a solid-state watch in which the time information exhibited on the electro-optic display has only two aspects (i.e., time-of-day and seconds), the minimum number of switches is three, in that by having a common switch or button to select either aspect of time information, it is still necessary to have two additional switches for the setting modes.
But when a four digit electro-optic time display also includes a read-out of calendar date, then additional switches are required. In a solid-state watch of this type, the read-out has three aspects, the first being "time-of-day" (hours and minutes), the second being "seconds" and the third being "calendar date"; each aspect being settable.
In order to reduce the number of switches required in a three-aspect display, it is now the practice in certain commercially available watches of this type, such as the Elgin "Minicon", to make use of two push-button switches which are so arranged that by pressing one button, the first aspect is presented, by pressing both buttons simultaneously, the second aspect is presented, and by pressing only the other button, the third aspect is seen. However, in addition to the two buttons, a setting switch is required, which switch when operated will advance the reading selected by the buttons.
Solid-state watches have been developed in which in addition to the previously mentioned aspects which appear in numerical form, the display is adapted to present data in an alphabetical format, such as the day of the week (Mon. to Sun.) or the name of the month (Jan. to Dec.). In this instance, the LED display elements are in nine-segment or in dot-matrix form capable of producing an alpha-numeric read-out. Here again, the number of switches required is determined by the number of display aspects.
The fact that in solid state watches the need for separate setting switches for each of the various readings unduly complicates the watch structure and makes it difficult for the user to carry out setting operations is recognized in U.S. Pat. No. 3,823,545. In this patent, selective setting is effected by a data input circuit which sequentially causes numbers to be displayed, each representing a reading to be corrected. Thus number "0" represents correction of the units of seconds, number "1" represents corrections of tens of seconds and number "2" represents corrections of units of minutes. When the numbers are presented, the user who wishes to correct a particular reading, presses a button to hold the appropriate number and to cause the reading selected thereby to advance. But in this arrangement, no means are provided to simplify the selection of the various time and calendar displays.
Thus in more sophisticated forms of solid-state watches, the switches or push-buttons entailed by the multiplicity of display aspects has reached a stage which, in practical terms, is approaching the unmanageable. The need for a multitude of aspect and setting switches all housed in a small casing, creates serious problems. Not only is it necessary to place these switches at accessible yet distinct positions on the casing, but it is also essential that each switch position be water proofed. And quite apart from these factors is the matter of human engineering and dexterity, for the average user, faced with a scattering of buttons and switches, finds it difficult to remember which button or switch serves what purpose, to say nothing of the problem of manipulating an individual button which is in close proximity to another button that is not to be pressed at the same time.